In the field of stage lighting, it is known to provide a memory facility into which can be stored information relating to the dimmer levels necessary to produce various lighting effects. This information is pre-stored, for example during a rehearsal, in a main processor herein referred to as the rack, and can be recalled (played back) during a performance by operating (cueing) various controls such as faders on a control console. It is preferably possible for the control console to be separable from the rack in order to permit its location at a chosen site from which the stage is visible. By means of such a memory control system complex lighting effects can be achieved, involving the simultaneous adjustment of the levels of many individual dimmers by the use of linked controls referred to as masters, which effects would otherwise be virtually impossible to synthesize at the time owing to the large number of simultaneous controlled adjustments which would be necessary.